Thanks for your contribution. we observed that the feature which you are requesting already exist on steemit.com.

" while making a post in Steemit, I have observed that as soon as we start writing the content the option of choosing Editor gets hided, not sure if it is bug or what refer below images, there is no option of Editor/Markdown available"

If you are actually experiencing this, then it's definitely a bug. which you may want to report because from my end, everything seems to work fine. kindly refer to the Gif below